The total fusion cross section for the system ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ + ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ has been measured over an energy range $27 \mathrm{MeV}\le E_{\mathrm{lab}}\le 70 \mathrm{MeV}$ by detection of the fusion-evaporation residues. In addition elastic scattering was measured at six energies and fitted by optical model calculations. The fusion cross section for the system saturates at 1150±50 mb. The data can be well described by the model of Glas and Mosel, using a reasonable set of parameters. The model of Horn and Ferguson also describes the data well if an appropriate charge radius is used. Comparison is made between these results and the fusion cross sections for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, which lead to the same compound nucleus. The results for ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ + ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ are quite similar to those for ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, and the differences between the fusion cross sections for these two systems and those for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ may be evidence for an entrance channel effect.

NUCLEAR REACTIONS ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$+${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, $E_{\mathrm{lab}}=27-70\mathrm{}$ MeV; measured ${\sigma }_{\mathrm{fusion}}\mathrm{}\left(E\right)\mathrm{}$; measured $\frac{d\sigma }{d\Omega }$ elastic scattering; data fitted with Glas and Mosel model, Horn and Ferguson model.

• Received 22 October 1979

DOI:https://doi.org/10.1103/PhysRevC.21.1819